Catalytic action of β source on x-ray emission from plasma focus -: art. no. 013504

The influence of preionization around the insulator sleeve by a mesh-type beta source (Ni-28(63)) for the x-ray emission from a (2.3-3.9 kJ) plasma focus device is investigated. Quantrad Si p-i-n diodes along with suitable filters are employed as time-resolved x-ray detectors and a multipinhole camera with absorption filters is used for time-integrated analysis. X-ray emission in 4 pi geometry is measured as a function of argon and hydrogen gas filling pressures with and without beta source at different charging voltages. It is found that the pressure range for the x-ray emission is broadened, x-ray emission is enhanced, and shot to shot reproducibility is improved with the beta source. With argon, the Cu K alpha emission is estimated to be 27.14 J with an efficiency of 0.7% for beta source and 21.5 J with an efficiency of 0.55% without beta source. The maximum x-ray yield in 4 pi geometry is found to be about 68.90 J with an efficiency of 1.8% for beta source and 54.58 J with an efficiency of 1.4% without beta source. With hydrogen, Cu K alpha emission is 11.82 J with an efficiency of 0.32% for beta source and 10.07 J with an efficiency of 0.27% without beta source. The maximum x-ray yield in 4 pi geometry is found to be 30.20 J with an efficiency of 0.77% for beta source and 25.58 J with an efficiency of 0.6% without beta source. The x-ray emission with Pb insert at the anode tip without beta source is also investigated and found to be reproducible and significantly high. The maximum x-ray yield is estimated to be 46.6 J in 4 pi geometry with an efficiency of 1.4% at 23 kV charging voltage. However, degradation of x-ray yield is observed when charging voltage exceeds 23 kV for Pb insert. From pinhole images it is observed that the x-ray emission due to the bombardment of electrons at the anode tip is dominant in both with and without beta source. (c) 2006 American Institute of Physics.